big problem smoke and fire.

8O alright guys i need help bad i finally got the bike started runnin good i got it idled down then i go to take a ride i put it in gear start to take off and it dies on me after a few more attempts smoke starts to come out from the crankcase on the left side and a fire breaks out right under the crank case... any thoughts opinions or advice on whats going on here?

thanks guys.

big rob

by the way it is a 85 maxim x xj700

 

it was smoking alot before i tried to ride it when i was just trying to get it running but it just looked like it was coming from the pipes just burning off oil that had dripped down also from the top of the engine at the spark plugs gunked up and at the exhaust pipes connection at the engine. but it has been smoking like a cafe shop in amsterdam as soon as it warms up it goes to smoking thats why i thought it was just burning off oil and gunk.

 

sounds like just an oil fire. maybe your carbs were leaking? its hard to pin point what caused the fire just by saying hey it smokes and caught on fire. what is the list of things you have done to the bike previous to attempting to ride it?

 

Wow! that's no fun. If you actually had flames down there...well then you had fuel and either a spark or your pipes were over 480F to autoignite.

If your pipes weren't fully heated up then I would suspect a plug wire is grounding to your engine (arcing) and you had fuel down below for some reason-so the vapors reached the arcing wire and the flame front followed the vapor trail back down to the source.

Have you changed your oil (it may have fuel in it) inspected your petC for leakage and around your carbs? Did you smell fuel at any time?

 

is there fuel in the crankcase?

 

yea after reading forms and post i went and smelled the oil it smells a little strong with gas. so far the things i've done this bike i took the tank off to drain the bad gas just put in new high octane gas it has been sitting for about 3 months now i have been trying to get it running had a wiring problem and a starter problem fixed the starter and got a new ground wire from the engine to the battery. it was running fine but i still had to get a new battery so i didn't take it off the kickstand until today. it has been outside covered up by a tarp. so i'm guess moisture gets to it may have gotten water in it some where the muffler spits a little at high revs.

 

Sounds like you've learnt a hard lesson! Suggest you sort out that petcock and check the floats in your carbs. Both of these things need fixing before you do ANYTHING else. Oh and welcome to the forum!


http://xjbikes.com/Forums/viewtopic/t=14692.html

 

No, what happened is you have a carburetor float problem, most likely enabled by a petcock that's not shutting off properly.

If your oil smelled of gasoline, your carbs are dumping fuel into the crankcase, which will then cause gas-laden oil to puke out the breather.

You need to get this all sorted out before you try to ride the bike or even run the motor or you'll blow it up (either figuratively or literally, the way you're going.)

GET A SERVICE MANUAL. Go through the entire "maintenance" section and do every single thing, in order. Until you do, you won't be able to consider the bike safe nor reliable, even if you do get it running. It's nearly 30 years old; you have some work to do.

 

alright thanks guys i've been wanting to take the carbs off and clean them just honestly didn't want to go through the hassle but i i will take them off clean them up and look at what the manual cd says about the petcock. yea i know this bike has been one hell of a learning experience but i'm not gonna give up on it i'll get it running good and strong or it will kill me one or the other.

 

Also, don't dismiss a likely electrical problem. The only place where you should get enough heat to start a fire is in the combustion chamber, or in the exhaust. Does the outside of the exhaust pipes actually get hot enough to auto ignite fuel vapor?

Just as an example, my friend dropped my bike, which led to gas in the airbox. My drain tube wasn't routed properly, and on a hot 90+ F summer day, the drain tube poured out onto the muffler joint, much to my dismay, but without igniting (I've since fixed that routing).

If something is catching on fire, either something combustible is coming in contact with a spark (spark only belongs in the cylinder), or a wire is shorted and overheating, causing combustion. How are your fuses?

 

all the fuses seem fine which i don't understand why my starter button doesn't work i took it apart and it seemed fine but the only wire that i have a problem with is a black wire coming out of the wiring harness beside the battery box up top there is nowhere to connect it to and it has been cut down to a bare wire so i don't know what kind of connector it had on it to begin with.

the fire ignited directly under the crank case along the gear shifter on top of the mufflers right before you get to the oil plug. it ignited burned for a second and went out.

 

i was looking at it i'm going to have to take the gas tank off to take the carbs off right? the manual says nothing about it but i don't see any other way around it.

 

Yes, tank comes off for any maintenance that goes on underneath it. Which manual, usually, the first couple of instructions will say something like, remove gas tank as shown in chapterX. It won't go through the steps in the same procedure as carb removal.

There's a whole host of wires and cables under there too, so it's a good chance to inspect those as well.

MercuryMan is on the right track. The heat or spark source doesn't need to be too close to the fuel leak, since the fuel vaporizes, the vapors can make their way to the heat/spark source, ignite, and a flame can travel back to the fuel source.

Black wires, if stock on the wiring system, are ground wires. If it's something the PO added, then it could be anything. Test it for voltage with the key on to give you some hints.

 

yea i figured as much it's just cold outside and i don't have a garage i can do all of this in that cold wind isn't too friendly when your trying sitting down trying to take something apart. but i will take it all apart and clean up the carbs and see what i can figure out.